1. Field of the Invention
The present invention relates to an electronic endoscope system including an endoscope having an insertion portion configured to be rotatable with respect to an operation portion.
2. Description of the Related Art
Conventionally, endoscopes having an insertion portion configured to rotate with respect to an operation portion have been proposed. Such an endoscope is provided with an insertion portion rotating dial, for example, at an operator's hand side of the insertion portion of the endoscope, and the insertion portion is configured to rotate through rotating operation of the insertion portion rotating dial.
Specifically, Japanese Patent Application Laid-Open Publication No. 2005-254002, for example, discloses a configuration in which an insertion portion rotating portion (21) which rotates integrally with an insertion portion (2) is provided, and the insertion portion (2) can be moved rotationally with respect to an operation portion (3) through twisting operation of the insertion portion rotating portion (21).
In such a configuration, an operator inserts an insertion portion of an endoscope into a subject while rotating an insertion portion rotating dial, as necessary. At this time, the operator confirms the rotation angle of the insertion portion by visually checking the insertion portion rotating dial.
When the endoscope is an electronic endoscope, the operator operates the endoscope while checking an image obtained from the electronic endoscope on a monitor.
Therefore, the operator views the monitor when performing insertion operation, and looks away from the monitor to visually check the insertion portion rotating dial when confirming the rotation angle of the insertion portion, that is, it has been necessary for the operator to change his or her line of sight.
In order to address such a problem, Japanese Patent Application Laid-Open Publication Nos. 2010-234058 and 2009-50540, for example, disclose an endoscope capable of rotating an insertion portion (12) with respect to an operation portion (16) through rotation operation of a rotation knob (19), wherein a cover indicator (27) and a knob indicator (36) are provided to a cover (25) of an operation portion housing (23) and a rotation knob (19) on a proximal end side of the insertion portion (12), respectively. According to such a configuration, when the knob indicator (36) is brought into line with the cover indicator (27), the operator can recognize that the insertion portion (12) is in the neutral position with respect to the operation portion (16). Furthermore, these publications recite a technique for providing a force amount changing mechanism for changing a rotation force amount required for rotation depending on the rotation angle of the insertion portion (12). Such a mechanism enables the operator to force-sensitively perceive the rotation angle of the insertion portion (12). Therefore, according to the technique recited in these publications, whether the rotation angle of the insertion portion is in the neutral position or not can be confirmed by visual check and perceived by the operator sensing the force amount.